[dj_mc_merlin]

It was like that for me too when I worked 9-5 (or more like 6). Now I work "biphasal" days so to speak, from 12:00-16:00 and sometime later in the evening for a couple hours. I find that splitting it up helps me be more productive, I have more of my "software development energy" to spend. I'm lucky that my work offers very flexible hours since we hire around the globe and nobody in my team minds that I review their MRs in the middle of the night.

I usually use the day hours as "open office time" for support requests and meetings, and the later time as "proper work time". This helps me avoid context switches.